Abstract: When the photovoltaic DC boosting delivery system starts,there is an overcurrent problem on both the boost side and the inverter side, and the active clamp BFBIC module has a high switching frequency, which causes serious system loss and reduces operational reliability. Aiming at the above problems, this paper proposed a DC boost external delivery system for IPOS type photovoltaic power station. By analyzing the principle of system startup overcurrent, the soft start control strategy of the system was proposed. At the same time,a ZVS soft-switching control strategy was proposed for the active clamp BFBIC switch, and the constraint conditions were theoretically derived. Through the coordination of the two control strategies,the soft start of the system and the soft switching of the active clamp BFBIC are realized,ensuring the safe and stable operation of the system. Finally,a 1 MW/±30 kV IPOS photovoltaic DC boost delivery system model was built in Matlab/Simulink. The simulation results verify the effectiveness of the new control strategy.